In animal parasitic nematodes a family of glycosylated proteins called mucins is a component of the cuticle''s surface coat and these proteins are thought to be important in the evasion of the immune response. Mucins are a family of proteins of high molecular weight with greater than 50 percent of their mass being made up of glycans. They are rich in the amino acids proline, serine and threonine and can either be secreted or membrane bound. Eleven mucin-like genes (H43E16.1, F59A6.3,
cpg-1,
let-653, F35E12.7,
cwp-4, K06A9.1, H02F09.3, C12D12.1, C26G2.2 and F16F9.2) were knocked down by RNAi and screened for changes to glycans present in the mouth, pharynx, grinder, surface coat, vulva and rectal regions using four different lectins (wheat germ agglutinin, WGA; Concanavalin A, Con A; Tetragonolobus purpurea agglutinin, TPA; Peanut agglutinin, PNA). Results showed different patterns of lectin binding to each of the structures scored and the binding was variable between replicated individuals. Generally, lectin binding was low across wild type worms with the exception of TPA which appeared to have a higher level of recognition to the cuticle and rectum. The lectins WGA, Con A and TPA bound to the vulva of wild type worms more successfully than PNA. Knocking down mucin-like genes with RNAi affected lectin binding patterns and the effects differed between the different structures scored. For example, knocking down H43E16.1, F59A6.3, C26G2.2 and F16F9.2 increased the binding of PNA to the grinder but whereas H43E16.1, F59A6.3 also showed increasing binding of PNA to the cuticle, C26G2.2 and F16F9.2 were no different from wild type worms. Conversely, knock-downs of F35E12.7,
cwp-4, K06A9.1, H02F09.3, which increased the binding of PNA to the cuticle showed binding similar to wild type worms in the grinder, whereas, C26G2.2 and F16F9.2, which had increased binding to the grinder, were no different from wild type worms. The cuticle forms an important barrier between a nematode and its environment and reducing mucin-like proteins appears to affect the surface coat of Caenorhabditis elegans in complex ways.